OBJECTIVE:
To assess the prevalence of acute bronchitis, rhinitis, and sinusitis among
children and adolescents and identify associated factors.METHODS: This is a population-based, cross-sectional study. A household
survey was conducted with 1,185 children and adolescents from the city of São
Paulo (Southeastern Brazil), from 2008 to 2009. The participants were selected
by means of probability sampling, stratified by sex and age, and by two-stage
cluster sampling. For the adjusted analysis, multiple Poisson regression was
used.RESULTS: Of the respondents, 7.3% reported acute bronchitis, 22.6% rhinitis
and15.3% sinusitis. After the adjusted analysis, the following characteristics
were associated with self;reported acute bronchitis: age 0 to 4 years (PR=17.86;
95%CI: 3.65;90.91), 5 to 9 years (PR=37.04; 95%CI: 8.13;166.67), 10 to 14 years
(PR=20,83; 95%CI: 4.93;90.91), allergy (PR=3.12; 95%CI: 1.70;5.73), black and
mixed-ethnicity (black and white) skin color (PR=2.29; 95%CI: 1.21;4.35), and
living in a household with 1 to 3 rooms (PR=1.85; 95%CI: 1.17;2.94). As to self-reported
rhinitis, the following characteristics were associated: age 10 to 14 years
(PR=2.77; 95%CI: 1.60;4.78), 15 to 19 years (PR=2.58; 95%CI: 1.52;4.39), allergy
(PR=4.32; 95%CI: 2.79;6.70), asthma (PR=2.30; 95%CI: 1.30;4.10) and living in
flats (PR=1.70; 95%CI: 1.06;2.73). Concerning self-reported sinusitis, the following
characteristics were associated: age 5 to 9 years (PR=2.44; 95%CI: 1.09;5.43),
10 to 14 years (PR=2.99; 95%CI: 1.36;6.58), 15 to 19 years (PR=3.62; 95%CI:
1.68;7.81), allergy (PR=2.23 (95%CI: 1.41;3.52) and obesity (PR=4.42; 95%CI:
1.56;12.50).CONCLUSIONS: Respiratory diseases were more prevalent in population
groups with defined characteristics, such as age group, self-reported diseases,
type of household and obesity.

Respiratory diseases
characterized by acute bronchitis, (allergic) rhinitis and sinusitis (chronic
rhinosinusitis) are important causes of morbidity in children and adolescents
around the world. In the United States, these diseases were responsible for
the highest number of visits to outpatient health services for people up to
15 years old between 2001 and 2002. In addition, they exercise an important
pressure on the health services and are responsible for frequent school absenteeism.ª

These respiratory
diseases also have a prominent position in Brazil. The recent increase in the
cases of hospitalizations of children and adolescents possibly occurs due to
bronchial irritation from infectious and noninfectious causes, like atmospheric
pollutants, cigarette smoke and other allergens.11

The prevalence
of episodes of acute bronchitis is 5% per year in the United States. It is one
of the most common infections in children younger than five years and it is
responsible for numerous hospitalization cases.12

According to the
last Brazilian consensus,b
rhinitis is described in the literature as one of the most frequent chronic
diseases in childhood. Although little importance is given to it, it produces
great discomfort and can be associated with serious problems like sleep apnea,
asthma and repeated respiratory infections. The mean prevalence of symptoms
related to allergic rhinitis in Brazil was 29.6% among adolescents (13-14 years)
and 25.7% among schoolchildren (six-seven years) between 2002 and 2003. Brazil
is in the group of countries with the highest prevalence of allergic rhinitis
in the world.18

Rhinitis and sinusitis
are quite common in clinical practice and are conditions which are frequently
associated. It is estimated that sinusitis affects approximately 31 million
people annually in the United States, one of the most prevalent affections of
the upper airways, with high financial cost to society.10

Both sinusitis
and rhinitis may mean decrease in the quality of life and aggravation of comorbidities;
it addition, they may demand significant expenditures on health. They may also
create indirect costs to society, as the lost school days can reduce school
learning. Although rhinitis and sinusitis frequently occur in the population,
little is known about the epidemiology of these diseases. The same can be said
about acute bronchitis. The absence of a standardized method to identify them
in epidemiological studies is an important limitation to obtain these data.c

Although respiratory
diseases in childhood and adolescence are common, information about the frequency
and distribution of respiratory diseases in children and adolescents is scarce
in Brazil. Regarding the municipality of São Paulo (Southeastern Brazil),
there are few population-based studies about estimation of the prevalence of
these respiratory diseases and associated factors for these age groups.5
Population health surveys play an important role in the knowledge of current
aspects about the population's morbidity situation. Health information subsidizes
actions supported by objective data backed by scientific evidence. Population
health surveys carried out periodically are important to generate information
that is not obtained in continuous national records, and are fundamental to
plan and evaluate the policies of prevention and control of health problems
and of health promotion in the municipal or regional level.2

The aim of this
study was to estimate the prevalence of acute bronchitis, rhinitis and sinusitis
in children and adolescents and to identify associated factors.

METHODS

Cross-sectional,
population-based study with data from the 2008 Inquérito de Saúde
no Município de São Paulo (ISA - Capital 2008 - Health Survey
in the Municipality of São Paulo), from 2008 to 2009. The sample of ISA
- Capital was of 3,271 people, and for this study, children and adolescents
were selected, totaling 1,185 individuals aged between zero and 19 years.

The participants
were selected by probability sampling, stratified by sex and age, and by two-stage
cluster sampling: census tracts and households. Seventy sectors were drawn from
Pesquisa Nacional por Amostra de Domicílio (PNAD-2002 - National
Household Sample Survey), which sampled 267 urban census tracts in the municipality.d

A questionnaire
structured in 21 thematic blocks whose majority of questions was closed was
administered to the drawn person or to the mother/guardian, for children younger
than 12 years.e The interviews
were conducted by trained personnel who were supervised during the period of
the survey. To ensure quality control, new interviews were conducted by telephone
or directly in the households for those without telephone, based on a random
sample of 5% of the interviews. The non-response rate was 22.5% and there was
7.3% of vacant households or households whose inhabitants refused to inform
if anyone belonging to the age group lived there.

The dependent variables
were self-reported acute bronchitis, rhinitis and sinusitis (yes; no). The independent
variables were: sex, age, skin color, level of schooling of the head of the
family, income of the head of the family, characterization of the household,
type of household, number of rooms, sewage disposal, presence of dogs in the
household, of cats, presence of allergy, of asthma, body mass index (BMI,f
calculated according to reported weight and height), hospitalization in the
12 months before the interview, and nights of hospitalization. For the BMI classification,
the criterion proposed by Centers for Disease Control and Prevention was adopted,
by means of the BMI curve according to age and sex. Low weight was considered
BMI below percentile 5; normal weight, BMI between percentile 5 and below 85;
overweight, BMI between percentile 85 and below 95; and obesity, BMI higher
than or equal to percentile 95.

The association
between the independent and dependent variables was estimated in the bivariate
analysis by the chi-square test, with level of significance of 5%. Prevalence
ratios were used, as well as 95% confidence intervals, and multiple Poisson
regression was performed for the adjusted analysis. The variables which had
p < 0.20 in the bivariate analysis were considered and those with p <
0.05 remained in the multiple model. Interactions between the variables of the
final model were examined. The effect of sample design was considered for the
analysis of surveys based on complex outlines in the analyses. The program SPSS
16.0 was utilized. It allows incorporating the distinct weights of the observations.

The participants
signed a consent document in which the aims of the research and the information
that would be requested were explained and the secrecy of the information was
guaranteed. The research protocol was approved by the Research Ethics Committee
of the School of Public Health of Universidade de São Paulo (Process
no. 381/2001).

RESULTS

Of the 1,185 interviewees
aged between zero and 19 years, 50.1% were women and 61.9% had white skin color.
In addition, 94% lived in households characterized as houses, 56.1% owned the
place where they lived and 60.1% lived in homes with four rooms or more. Dogs
were present in 42.3% of the households and cats, in 13.3%. The prevalence of
asthma was 9.1% (95%CI: 7.0;11.7) and of allergy, 21.1% (95%CI: 17.9;24.7) (Table
1).

Acute bronchitis
was significantly associated with age (p < 0.001), skin color (p = 0,007),
presence of allergy (p = 0.001), of asthma (p < 0.001), number of nights
of hospitalization (four to seven nights, p = 0.012), and with number of rooms
in the household (p = 0.004). Rhinitis was associated with age (p = 0.001),
with presence of allergy (p < 0.001), of asthma (p < 0.001), level of
schooling of the head of the family (p = 0.005), and with the characterization
of the household (p = 0.001). Sinusitis was associated with age (p = 0.002),
with BMIf (p = 0.014), presence
of allergy (p < 0.001), and presence of asthma (p = 0.009) (Table
2).

In the multiple
Poisson regression model, the following variables were associated with self-reported
acute bronchitis: ages from zero to four years (PR = 17.86; 95%CI: 3.65;90.91),
from five to nine years (PR = 37.04; 95%CI: 8.13;166.67), from ten to 14 years
(PR = 20.83; 95%CI: 4.93;90.91), presence of allergy (PR = 3.12; 95%CI: 1.70;5.73),
black and mixed-ethnicity (black and white) skin color (PR = 2.29; 95%CI: 1.21;4.35),
and one to three rooms in the household (PR = 1.85; 95%CI: 1.17;2.94) (Table
3). The interaction test was not significant among the independent variables.
Age and skin color did not modify the association for presence of allergy (p
= 0.998 and p = 0.528, respectively), and number of rooms in the household did
not modify the association for skin color (p = 0.187).

The following variables
were associated with self-reported rhinitis: ages ten to 14 years (PR = 2.77;
95%CI: 1.60;4.78), 15 to 19 years (PR = 2.58; 95%CI: 1.52;4.39), reporting to
have allergy (PR = 4.32; 95%CI: 2.79;6.70), reporting to have asthma (PR = 2.30;
95%CI: 1.30;4.10) and living in a flat (PR = 1.70; 95%CI: 1.06;2.73). There
was no interaction between presence of asthma and allergy (p = 0.196), and age
did not modify the association for presence of asthma (p = 0.840) and of allergy
(p = 0.687) (Table 3).

The estimated prevalence
for episodes of acute bronchitis found in the present study is similar to that
of the United States, around 5% per year. Acute bronchitis is one of the most
common infections in children under five, and it is responsible for the majority
of the causes of hospitalization.12 The United States performed more
than 5 million consultations for acute bronchitis between 2001 and 2002, and
classified it among the most frequent diseases in the outpatient health services.ª

In Germany, the
prevalence of self-reported bronchitis in children aged five to seven years
was 21.3% in Munich, 33% in Dresden and 31.8% in Leipzig between 1995 and 1996.
The prevalence of bronchitis was 24.4% in Munich and 36.8% in Dresden for children
between nine and 11 years.23 The prevalence of acute bronchitis for
children between five and nine years old was lower in the present study: 13%.

Age was associated
with acute bronchitis, mainly in the first years of life. Presence of allergy
was associated with acute bronchitis. This disease frequently refers to an infectious
process propagated by the upper airways and is a complication of rhinitis or
pharyngitis, more common in atopic (allergic) individuals.12 Black
or mixed-ethnicity skin color and living in households with lower number of
rooms were also associated with acute bronchitis. Although skin color relations
are not defined by a social group, ethnic differences are associated with social
inequalities and condition the way of living of groups of individuals. Thus,
blacks are considered more susceptible to respiratory infectious diseases. Agglomeration
and low socioeconomic level are important factors for acute lower respiratory
tract infections, as well as allergies and associated comorbidities, like asthma.17

The mean prevalence
of clinically diagnosed rhinitis in Europe was 22.7% (95%CI: 21.1;24.2) in 2001,
similar to the present study in São Paulo. The European countries that
were evaluated were: Belgium (28.5%; 95%CI: 24.5;32.5), France (24.5%; 95%CI:
21.0;28.0), Germany (20.6%; 95%CI: 16.5;24.6), Italy (16.9%; 95%CI: 12.9;20.9),
Spain (21.5%; 95%CI: 18.5;24.4) and England (26.0%; 95%CI: 20.3;31.7%).4
Rhinitis presents important variations in the prevalence indexes of its symptoms.
According to studies carried out in hundreds of cities in Africa, North and
South America, Asia, Australia and Europe, with 463,801 children aged 13 to
14 years, and in dozens of cities in the same regions, except for Africa, with
257,800 children aged six to seven years, the prevalence of rhinitis symptoms
varied from 3.2% to 66.6% and from 1.5% to 41.8%, respectively.20

The mean prevalence
of rhinitis in 20 Brazilian cities for children aged six to seven years and
for adolescents aged 13 to 14 years was 25.7% and 29.6%, respectively. For the
present study, the estimated prevalence of rhinitis for the age group between
five and nine years was 22%, and between ten and 14 years, 29%, similar to the
Brazilian mean. In São Paulo, the International Study of Asthma and Allergies
in Childhood (ISAAC) - Phase 3 - pointed prevalence of symptoms of rhinitis
(sneezing, coryza or nasal stuffiness present in the absence of a cold) for
children and adolescents of around 29% from 2002 to 2003. The prevalence of
rhinitis by medical diagnosis was 19.3% for children and 21.4% for adolescents,
values that are similar to the ones found in the present study.18

The presences of
asthma and allergy were associated with rhinitis. Batlles-Garrido et al3
(2010) found odds ratio 2.2 (95%CI: 1.22;4.02) times higher for rhinitis in
asthmatics when compared to non-asthmatic individuals, and for the presence
of atopy, the odds ratio was of 2.5 (95%CI: 1.93;3.42). Epidemiological studies
show that, many times, asthma and rhinitis coexist in the same person. At least
60% of the asthmatics have rhinitis and approximately 20% to 30% of the people
with rhinitis have asthma.7

Law et al15
(2003) stated that consultations in emergency services are responsible for 1%
of the direct costs with rhinitis, but account for 62% of the expenditures on
asthma in the United States. Rhinitis, intimately associated with asthma, is
a public health problem in many countries, which leads to the need of monitoring
its tendencies continuously. Clinical observation and data from the literature
show that the adequate approach to inflammation in the upper airways is indispensable
to the satisfactory handling of the asthmatic. People with rhinitis frequently
present a reduction in the quality of life, caused by sleep disorders, fatigue,
irritability, daytime sleepiness, and memory deficits. In addition, the financial
impact becomes higher when the related comorbidities are considered, like asthma,
sinusitis and allergies.7,16

Due to the coexistence
between allergic rhinitis and asthma, the importance of the upper airways infections
as an intensification factor for asthma and the importance of the presence of
rhinitis as a risk factor for sinusitis have been widely discussed. Rhinitis
is associated with worse control of asthma. This is interpreted as the expression
of one disease that affects simultaneously the upper and lower respiratory tracts,
probably due to common risk factors and pathogenesis.7,16

Living in flats
was associated with rhinitis, supporting the hygiene hypothesis, which interprets
the variation in the risks for allergic diseases as a reflex of the reduction
in the exposure to microbial agents in the early phase of life. According to
this hypothesis, the change to the modern lifestyle would be responsible or
co-responsible for the significant increase in allergic diseases in the last
decades. Strachan (1989)21 considers it as the only coherent and
biologically plausible explanation for the variations in allergy observed among
more or less numerous families, modern lifestyle (flats) or in farms and fields
(houses). However, the following aspects seem to contradict this hypothesis:
high rates of respiratory disease among the poor urban population in the USA
and in other industrialized countries, the lungs of many atopic children are
abnormal before the occurrence of any infection, and there is no evidence that
the incidence or type of viral respiratory infections have decreased during
the period of thirty years in which the prevalence of the allergic diseases
increased.24

As for sinusitis,
it is estimated that it affects one out of every six adults in the United States
and its diagnosis is considered one of the most common in clinical practice.
These statistics possibly underestimate the real prevalence in the country,
because approximately 20% of the affected people do not look for medical assistance.
Sinusitis by medical diagnosis presented prevalence around 10% in Europe, Japan
and in the United States in 2001.19 The prevalence of self-reported
sinusitis was higher in the present study. A large part of the studies about
the prevalence of this disease refers to the North American and European realities;
few studies present information on Latin America.c
Sinusitis generates a direct and indirect impact on the global economy due to
its high prevalence; also, it brings significant repercussions on the quality
of life of the affected children and their parents. Cunningham et al9
(2000) showed that parents of children with sinusitis attributed to them greater
physical limitation compared to children with asthma.

Allergy and obesity
were associated with sinusitis in the present study, and age presented dose-response
effect depending on the increase in the age group. Hoover et al13
(1997) observed odds ratio 4.3 (95%CI: 1.5;12.8) times higher for sinusitis
in allergic individuals when compared to non-allergic ones. According to consensus
recommendations, the term sinusitis has been replaced by rhinosinusitis due
to the numerous anatomic, histological and physiopathological relations between
the nose and the paranasal sinuses. There is no genetic predisposition to sinusitis;
however, there is family predisposition to allergies, which are considered the
main predisposing factors to sinusitis. The symptoms overlap and sinusitis rarely
occurs without other allergies. Evidences show that asthma, rhinitis (and other
allergies) and sinusitis would represent parts of one single inflammatory syndrome,
the "united airways disease". The risk factors that are most implicated in sinusitis
are the allergies and viral infections of the airways.1,7,13,16

No studies that
showed or explained consistently the association identified between obesity
and sinusitis were found. One of the possible interpretations refers to the
association between gastro-oesophageal reflux disease and respiratory symptoms
in children, a disease that is also related to presence of overweight and obesity,25
although there are controversies.14 On the other hand, the increased
presence of proinflammatory cytokines in obese individuals and these substances
would be related to the local and systemic inflammatory responses of the airways.6
Obese people present higher risks for asthma and other associated diseases,
like sinusitis and allergies, due to the relation between these respiratory
diseases and circulating levels of these cytokines, which are higher in obese
people. Nevertheless, little is known about the physiological, mechanic, immunologic,
genetic and environmental mechanisms that participate in the relation.8

Concerning the
study's limitations, self-reported morbidity may underestimate the prevalence
of respiratory disease due to memory bias and/or absence of diagnosis. To epidemiology,
estimating the prevalence of self-reported respiratory diseases in the population
is a simple and direct way of obtaining information about health and presents
good levels of agreement, reproducibility and cost-benefit when the results
of clinical evaluations are obtained, which can indirectly reflect the real
prevalence of the disease in the population.22

Table
4 synthesizes the final outcomes that are common, similar and specific to
acute bronchitis, rhinitis and sinusitis. Presence of allergy was associated
with the three diseases. Atopic individuals are more susceptible to the associated
comorbidities, and they frequently have more than one sensitized shock organ:
bronchial mucosa (asthma), nasal mucosa (rhinitis), conjunctiva (allergic conjunctivitis)
and skin (atopic dermatitis).1,16,c
Sinusitis and rhinitis exist without other associated allergies with lower frequency,
and acute bronchitis affects a higher number of atopic individuals. The age
group ten to 14 years was common among the three respiratory diseases. Household
aspects were similar between acute bronchitis and rhinitis. The hygiene hypothesis
can explain part of the high prevalence of rhinitis in those who live in flats,
unlike the relation between low number of rooms (one to three) in the household
and acute bronchitis, which can be related to low socioeconomic level, agglomeration
and low standard of living, which in turn can increase the risk of lung infection
by virus or bacteria, mainly among children.17 Black and mixed-ethnicity
skin color was specifically associated with acute bronchitis. Admitting that
the individuals' skin color determines their socioeconomic conditions, or that
ethnic differences are associated with social inequalities and condition the
way of living of groups of people, blacks can be more susceptible to infectious
respiratory diseases. Another specific outcome was the presence of asthma in
people with rhinitis. The current literature considers asthma and rhinitis as
expressions of the same disease, which affects, concomitantly, the upper and
lower airways.

Respiratory diseases
- rhinitis, sinusitis and acute bronchitis - are more prevalent in certain population
groups and are an important public health problem in children and adolescents.
Respiratory diseases in childhood and their impact on the health system generate
epidemiological studies to dimension the problem and to know, in addition to
their prevalences, the etiologic factors involved, so as to implement measures
to control these diseases and reduce the associated morbidity and mortality.
Allergic individuals from zero to 14 years whose skin color are black and mixed
(black and white) who live in households with few rooms were associated with
acute bronchitis; allergic individuals between ten and 19 years, asthmatic and
who live in flats were associated with rhinitis; and allergic individuals between
five and 19 years and obese were associated with sinusitis.